A package represents a box with a shipping label on it. Each shipment object can have many packages, each package with its own tracking code.
id - Integer - Unique id of the package
carrier - String - The carrier being used to deliver the package
service - String - The service level used for delivery i.e. Ground
tracking_code - String - The code used to track the delivery of the package
weight - Decimal - The weight of the package in LBS.
tracking_link - String - URL to track the delivery status of the package
eel_pfc - String - EEL of PFC -- Custom's identification for this package
customs_signer - String - User who shipped the package
contents_type - String - One of: merchandise, returned_goods, documents, gift, sample, other
contents_explanation - String - If other is the value of the contents_type property, this field is used to describe what the package contains
restriction_type - String - One of: none, other, quarantine, sanitary_phytosanitary_inspection
restriction_comments - String - If other is the value of the restriction_type property, this field is used to describe the restriction
customs_items - [CustomsItem] - Array of CustomsItem objects that are associated with this package